Policy makers, health care organizations, and health professionals are calling for expansion of nurse practitioner workforce in primary care to assure timely access for the American public. However, many obstacles to effective nurse practitioner primary care practice exist, including barriers at the organizational level, and there is lack of reliable and valid instruments to measure organizational climates to identify those barriers from nurse practitioners' perspectives. The Nurse Practitioner Primary Care Organizational Climate Questionnaire (NP-PCOCQ) is being developed through literature review, investigation of existing instruments, nurse practitioner focus group data, content validation, and pretesting. Five domains underlying organizational climate perceived by nurse practitioners are proposed: a) autonomy, b) professional status, c) empowerment, d) collegiality, and e) policy. Each NP-PCOCQ subscale measures one organizational climate domain through items asking nurse practitioners to rate their perceptions on a 4-point scale from strongly disagree to strongly agree. The purpose of this study is to examine the psychometric properties of NP-PCOCQ, and further refine and validate this survey instrument. Specific aims include 1) To examine whether the items on each subscale measure the intended construct fitting the data from nurse practitioners utilizing confirmatory factor analysis. 2) To further investigate and establish construct validity of the instrument through using item response theory models. A cross-sectional survey design with a sample of nurse practitioners from the Massachusetts Health Quality Partners Massachusetts Provider Database will be used. The sample will include nurse practitioners practicing in primary care settings in Massachusetts (n=713). Each nurse practitioner will receive a mail survey along with a cover letter and consent form explaining the study purpose, their rights as participants, and the confidentiality and anonymity of their responses. They will be asked to complete the survey and return it to the research team. Post card reminders and second mailing will be initiated to increase the response rate. SPSS, LISREL, and MULTILOG statistical software will be used for data entry and data analysis. Separate models will be estimated using confirmatory factor analysis for each organizational climate domain to demonstrate how the measures in each subscale measure the intended construct. Then using Samejima's Graded Response model in Item Response Theory the characteristics of each individual item will be investigated. These analytical procedures will assess the discriminant, convergent, and construct validity, and will produce sample invariant parameters. NP-PCOCQ may be used with various groups of nurse practitioners for conducting meaningful comparisons of organizational climates across practice sites and states increasing the utility of the instrument.